/// <summary>
/// Retrieves the <c>double</c> value of a <c>Number</c> value.
/// </summary>
/// <remarks>
/// <para>
/// This function retrieves the value of a Number value. It will fail with
/// <c>InvalidArgument</c> if the type of the value is not <c>Number</c>.
/// </para>
/// <para>
/// Requires an active script context.
/// </para>
/// </remarks>
/// <returns>The <c>double</c> value.</returns>
public double ToDouble()
{
double value;
Native.ThrowIfError(Native.JsNumberToDouble(this, out value));
return(value);
}